Piston and piston-valve of steam-engines



DNITED STATES PATENT OFFIDE.

THOMAS S. DAVIS, OF JERSEY CITY, NEW JERSEY.

PISTON AND PISTON-VALVE OF STEAM-ENGINES.

Specification forming part of Letters Patent No. 31,308, dated February 5, 1861; Ressued November 10, 1874, No. 6,128.

constructed according to my invention. Fig. 2, is a cent-ral section of the same. Fig. 3,

is a transverse section `of the same, and Fig. il, is an end view'of the packing ring.

Similar letters of reference indicate corresponding parts in the several figures.

My invention is more particularly designed for piston valves but may also be adopted for other kinds of pistons.

It consists in a certain construction of a piston whereby it is made as much as possi-V ble like a solid block yet capable of being set out to fit the cylinder in which it worksv and compensate for wear.

To enable others to make and use my invention I will proceed to describe its construction and operation.

A, is a single ring, of cast iron, brass or other metal, of a depth equal to the whole depth of the piston turned externally to a cylindrical form to t thecylinder, and having its interior turned out at one side concentrically to its exterior as shown at a, c1, in Figs. 2 and 4, for the reception within it of the flange of the solid head B, of the piston, and turned out at t-he opposite side in a similar manner as shown at c, in Fig. 2, for the reception of the follower C. The said ring has cut in its exterior at any point in its circumference a taper dovetail groove CZ, (l, for the reception of a dovetail wedge D, which is to be movable parallel with the piston rod; and from the middle of the back of the said groove the said ring is cut through as shown at e, in Figs. 2, 3 and 4, to permit it to be set out by the dovetail wedge, the outer face of which combines with the periphery of the ring to make a complete cylinder. The solid flanged head B, is driven tightly on or otherwise firmly secured to the rod E, and the follower C, is fitted to the rod and secured by a nut G, fitted to a screw thread on the rod, the said nut holding it close up to the face of the head B, and to the shoulder at theback of the recess c.

The Iiange has projecting from its periphery a short pin f, to'enter a notch g, in the interior of the recess a, of the ring; and the follower C, has a similar pin to enter a similar notch in the recess c. These notches and pins prevent the head B, the follower C, and ring A, from turning independently of each other.

The head B, and follower C, are received entirely within the ring A, so that the peripherical surface of the piston is unbroken except at the junction of the wedge D, and the piston is almost like a solid block, though it can be expanded and set out against the interior of its cylinder as required to make it t and compensate for wear, by means of the wedge D.

To provide for the convenient adjustment of the wedge D, I employ a screw H, screwing through a tapped hole in a lug L, at one end of the wedge and having a ournal 2', so fitted to a bearing in the ring A, as to be capable of turning freely but not moving longitudinally. This screw is fitted with a jam nut y', to secure the wedge in any position in which it may have been adjusted.

Instead of dividing the ring in one place only and using a single wedge I propose in large pistons to divide the ring in three or more places and use a corresponding number of wedges.

A very important feature of this invention consists in the dovetail wedge opening in a direction parallel with the axis of the piston. By the use of a wedge fitted and applied in this way I am enabled to make a steam tight joint in the simple ring and so dispense with the necessity of two rings.

IVhat I claim as my invention and desire to secure by Letters Patent is- The construction of a piston valve or other piston with a single expanding ring A, having the head B, and follower C, fitted to its interior and furnished with one or more dovetail wedges D, all substantially as herein described whereby it is made to have the character of a solid block but yet capable of being expanded in a lateral direction.

THOMAS S. DAVIS. Vitnesses M. M. LIVINGSTON, B. Mix. 

